The subject matter disclosed herein relates to fuel nozzle flashback detection.
A combustor of a gas turbine engine has a combustion zone defined therein and includes one or more fuel nozzles that provide combustible materials to the combustion zone. The fuel nozzles include arrangements of one or more burners that each have passages defined therein through which the combustible materials, such as mixtures of fuel and air, travel toward the combustion zone. As the combustible materials reach the aft ends of the burners, they are ignited and combust. Generally, this combustion occurs within the primary and secondary recirculation zones of the combustion zone and, while, temperatures at the burners can reach relatively highly elevated levels, these temperatures are usually within established temperature parameters for burner operation without significant damage.
Occasionally, however, flashbacks occur. During flashbacks combustion of the combustible materials takes place abnormally close to or within the burners and temperatures at the burners exceed the established temperature parameters. Since the burner components are not typically designed to withstand such conditions, damage to the burners and the fuel nozzles can ensue. This damage may necessitate a costly shutdown of the gas turbine engine, repairs and/or replacement of the burners and the fuel nozzles.
Mitigating a likelihood of a flashback for any particular fuel nozzle or burner can involve designing the fuel nozzle with a 20% margin on burner tube velocity for given fuels. That is, each particular fuel nozzle is designed for use with selected fuels with the expectation that certain quantities of those fuels would be supplied to the fuel nozzles at certain velocities during gas turbine operations. Drawbacks associated with the 20% margin exist, however, in that alternate fuels cannot be substituted for the given fuels at a later date without, at least, significant testing and damage risks.